In recent years, servers that provide games to portable devices through a communication network have become available. The games provided by the servers include those that accept participation of a plurality of users (a so called “social game”).
Japanese Laid Open Patent Publication No. 2013-225290 discloses a social game in which the user thereof can build a friendship with another user for the game to participate together in the game. For example, the user can fight an enemy in the game in cooperation with another user with whom the friendship has been built.
In the social game according to Japanese Laid Open Patent Publication No. 2013-225290, in order for the user to build a friendship with a specific user and start the game, the user has to be registered in the same social networking service (SNS) in which the specific user is registered. In addition, the user has to go through a complicated and troublesome procedure to build the friendship for the game directly with the specific user.
It is an object of the disclosed control method, control program, and computer to allow a user to easily start a game on the basis of a relationship among users, without the need to go through a complicated and troublesome procedure.